Question
i have a back yard that is mostly weeds: thistles, sand burs and plain weeds.  The ground is sand.  I live in Pensacola, Fl.  What I want to know is 1.  do I kill the weeds before putting down grass seed?  2.  if so, what do I use  3.  what kind of grass seed works best in sand?  4.  should I add some dirt to the sand?  Thank -you for your time.

Answer
Hi Cori,
Thanx for your question.  I used to live in Ft. Walton Beach back in the early to mid-80s.  I really like the area and spent a lot of time in Pensacola.

I'm not a lawn expert by any means.  However, I did find a publication from the University of Florida on lawn care that I think you will find helpful.

http://edis.ifas.ufl.edu/lh013

In my opinion, the first thing to do is get rid of the weeds.  I remember the sandy NW Florida soil.  You may want to rent a tiller and till the soil.  Bear in mind that tilling disturbs seeds and will cause quick germination of weed seeds so, you'll have to work fast.  You can ask for advice on pre-emergent weed killers that would be safe for you to use on your yard.  Once that has been treated then you can seed the yard and protect the seed with straw.  If I were you, I'd contact the Escambia County Extension (see contact info below) and I believe they have someone there you can talk to first-hand.  They can also give you recommendations for grass like Centipede or St. Augustine or something like that which is good for sandy, Southern soils.

http://escambia.ifas.ufl.edu/

I hope this helps.
Tom